1. Field of the Invention
The present invention relates to storage cell networks for the Mask ROM of IC memory products and more particularly to a high density NOR type read only memory data cell and reference cell network, which comprises a data cell for storage of data and a reference cell for accurate reading through contrast process, so as to achieve high density of storage operation.
2. Description of the Prior Art
Regular Mask ROM cell networks are generally constructed according to two different structures, one is of NOR type and the other is of NAND type. The NOR type can shorten the delivery time because of its late processing of code implantation. However, its manufacturing cost is relatively increased since it requires more contacts which increase the area of cell (low density). On the contrary, the NAND type requires less contacts and can relatively increase the density and reduce the manufacturing cost. However, the processing of code implantation must be completed at the initial stage in NAND type and longer delivery time will be required.